10/12 Meter Modification Instructions. AL (not A or B). The AL needs a kit to modify for 10/12 Meters. Write to us for details. All other units DO NOT require. Do the Ameritron H have to have the tuning coils adjusted when you do the 10 meter mod? I have not done the mod on my H and. the al & h mod is SIMPLE. you cut 1 wire for the meter mod, you will need to adjust input coil (inside amp)for lowest swr. if you do.
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The Ameritron ALH is an attractive choice as an entry level amplifier for the low budget amateur operator. Maybe the Yaesu linear does not like Svetlanas, I did not analyze its circuit. Then you can reinstall the tube socket sub chassis back into the main chassis with the 8 screws you removed from the bottom of the amplifier. Jeter a hole just large enough for a mounting screw. The directions say to snip a green wire off the 10 meter slug coil. The ALH has ameritronn essential design elements for a clean, stable signal.
When I finished with this amp, I metsr a good solid watts CW on 80, 40, and 20 meters. If you apply RF drive by transmitting, the grids will see that, with NO plate current.
Copper Talk: Ameritron AL
This cutoff bias mod appears to me to be logical at least, since it directly addresses the problem. At this point, I do not know how to fix the clicking problem other than using selected tubes. On the other bandthe SWR will be high and is an internal tuner required for full ouput.
I did not try any of this, so I have no comment. The bread always falls jelly side down. One is soldered to the pc board near the slug and the other loops over the pc board and solders on the back of the pc board. If your meter is not good at peak power, do not push the amp harder to make it look good on your meter. It is much easier to get VHF performance from those external anode ceramic tubes with their short internal leads, instead of taller glass tubes.
I put it in, after we encountered a clicking noise in the receiver in amplifier standby mode. This is the classic definition of instability.
Ameritron ALH 10m Mod | QRZ Forums
There is a lot 1 internet hype about parasitic suppressor design. Here are the W8JI instructions for the transformer taps for correct high voltage: Another did not move the tube tester needle. Then I tested the output power on various bands, and let the plates get hot with a lengthy SSB transmission at full specified power. See how close they are to the metal standoff at the left? It is not a guaranteed protection, but in most cases it increases your chances of amplifier survival by limiting the energy stored in the capacitors, which discharges through the tube arc.
The bleeder resistors will still discharge the filter capacitors if you turn off the AC as before.
Do not use a junkbox resistor for this. Click ameritroh any photo on this page to enlarge emter. I would encourage you to spend the extra money to get the ALH instead of the 3 tube model, if those were your options.
That is much easier with the whole subchassis completely removed. If not using the safety switch jumper, the simplest way to safely operate the amp temporarily is to put the cover back on, securing it with a single screw nearest the safety switch.
To put a db in perspective, it is the smallest change in power that is barely discernable, and then not by everyone. But the gas arc tube protectors are firing at VDC.
Ameritron AL-811H 10m Mod
The long wire to be replaced by coaxial cable RGso that the length is converted into a small capacitance in parallel with the load capacitor. These normally do not conduct except in the case of an internal tube arc, which may occur in Chinese tubes. I took out the other support brace after I marked the location for the mounting hole to drill it. The Warrior also used neutralization. The seller KNEW its condition, and that is why he dumped it.
In the meantime, avoid the cheapest priced products. Given its damage in the depicted tubeI think mos caused by parasitic metterwhich led to a high voltage.
Use a test clip to jumper the open contacts. Even if you could correct those problems, the A was designed as an audio tube, and internal lead lengths are excessive for full performance above 20 MHz. In this case the simplest modification is to add a The W8JI ohm resistor mod increases the drive power from about 40 watts to 45 watts on 80, mteer, and 20 meters.
You will never again find tubes of the quality standard of RCA or GE, but the new Chinese tubes from reputable sources are a good value. I was able to salvage the plate choke in this amp because I had some unobtainium Q Dope, a special low loss polystyrene cement.
Doing this kind of work with high voltage present is not for the inexperienced. My friend made a reasonable attempt, but knew when to quit. Driving this amp harder than watts CW on 80, 40, and 20 meters or about W CW output on 10 meters is unreasonable, and reduces tube life without gaining any signal level noticeable at the receiving end.